1. Field of the Invention
This invention relates to electronic projection systems and more particularly to electronic projection systems for high definition television systems which have a fluid therein which has an increased resistance to damage from projection system radiation.
2. Description of the Prior Art
The prior art is represented by DE-OS No. 22 03 576 which is equivalent to U.S. Pat. No. 3,715,494 and which discloses an electronic projection system. There, a deformable medium used as a control coating for a light valve must meet optical, hydromechanical, hydrodynamic and electrical requirements, and must be as insensitive as possible to the damages caused by radiation which are unavoidable on account of the electron beams acting as controlled variables on the medium. The additive, a 9,10 anthracene derivative, used to reduce damage to the deformable surface according to this prior art, when used with a polybenzyl-toluene material disclosed in U.S. Pat. No. 3,288,927 as a basic material, leads to an increase in the service life by a factor of more than 16.
On the basis of purely practical considerations, the absolute value for the service life of such a medium or fluid should be on the order of 10,000 hours. This value, given an operating time for a light valve projector of 5 hours/day, corresponds to a service life of 2,000 days, or approximately 5 years. It can be surmised that such values are reached or exceeded by known media for control coatings.
The number of competitors worldwide in this special field is small. The applicants and assignees of the present invention have drawn on the competitors; experience and results achieved over approximately two decades and have been engaged, in new research and development work, which research is concerned with large screen reproduction of high-resolution color television pictures such as HDTV (High Definition Television). Reports on the possibilities of light valve large-screen projection for HDTV have appeared, for example, in the publication FREQUENZ, No. 37 (1983) 11/12, Pages 300 to 306, along with an article in the same publication concerning a light valve projector for HDTV having a luminous flux of 1,600 lm at 400 W lamp output, No. 39 (1985) 9, Pages 257 to 262.